This invention relates to a process for sterilizing food stuffs and an equipment therefor, a process for packing and sterilizing food stuffs and packing receptacles therefor and a process for sterilizing and freezing food stuffs and an equipment therefor. Food stuffs mentioned here mean edible products which have to be sterilized because of public health.
Previously, various processes were used to sterilize food stuffs, and a process for sterilizing food stuffs with the aid of ozone was a typical one of the processes. In the typical process, an ozone solution, which has been produced by bubbling water with ozone gas, was used to preserve, for example, fishes, fresh vegetables which have been cut etc., while ozone gas was used to sterilize vegetables, fruits etc. The process with the aid of the ozone solution was superior to the process with the aid of ozone gas, because the former had stronger germicidal force than the latter, and because the ozone solution was permeable to the inside of food stuffs.
However, in the process with the aid of the ozone solution the ozone solution was directly in contact with the food stuffs, and as a result, there was a problem that the food stuffs to be treated should be limited. On the other hand, in the process with the aid of ozone gas its germicidal force was weak, with the result that it was necessary to increase the density of ozone. Since the force of permeation of ozone gas little, only the surface of food stuffs could be sterilized, and since the force of oxidation of ozone in high density was strong, the food stuffs changed color and emitted an offensive smell. Accordingly, there was a problem that the process with the aid of ozone gas was hampered by a lot of restrictions.